Explosive anchor firing device

ABSTRACT

An anchor construction wherein an explosive charge propels anchor members into the ocean floor. It includes means for firing the charges a predetermined period of time after the device has reached the ocean floor, such means operating without the use of any command link between the anchor and the surface and being capable of postponement if the anchor construction is lifted from the floor before the charge is ignited.

United States Patent 206.1, 207, 208 (R), 208 (A); 175/6; 175/5-- 10, 26, 27, 40, 45; 340/282; 340/267; ZOO/61.45, 61.48, 61.49, 61.52; 325/1 16 [72] Inventor John R. Thompson [56] References Cited 7 Camrillo, Calif- UNITED STATES PATENTS g5; 3 3 1 3,207,1 1s 9/1965 Anderson 1 14/206 Q [45] Patented Mar. 9 3,276,368 10/1966 Tower 114/206 [73] Assignee the United States of America as represented Primary Examiner-Milton Buchler by the Secretary of the Navy Assistant ExaminerF. K. Yee

Attorneys-Edgar J. Brower, Q. Baxter Warner and Gayward N. Mann [54] f i t g FIRING DEVICE ABSTRACT: An anchor construction wherein an explosive w 8 Figs charge propels anchor members into the ocean floor. It in- [52] U.S. Cl 114/206 eludes means for firing the charges a predetermined period of [51] Int. Cl B63b21/28 time after the device has reached the ocean floor, such means [50] Field of Search 114/206, 0 eratin without the use of any command link between the anchor and the surface and being capable of postponement if the anchor construction is lifted from the floor before the charge is ignited.

PATENTEU MAR 91971 SHEET 1 OF 2 Fig.

. INVENTOR JOHN R. THOMPSON Y M fl w CQ/a wgfm PAIENTED MR sum SHEET 2 OF 2 Fig. 2

EXPLOSIVE ANCHOR FIRING DEVICE STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION 1. Field of the Invention V This invention relates generally to anchor constructions for mooring ships or other structures and particularly to constructions wherein anchor members are propelled downwardly into the ocean bottom a predetermined period of time after the anchor has reached the floor of the body of water in which it submerged.

2. Description of the Prior Art Previous anchor constructions of this character employed anchor member propelling devices which required a command link between the anchor and a surface vessel. This link is generally provided by either a hard wire coupling or by ultrasonic transmission to a complex receiving system positioned on the anchor. Such devices are generally unacceptable because long length of wire are very difficult to handle aboard ship and ultrasonic devices may be vulnerable to accidental firing when influenced by stray radio frequency fields such as electromagnetic fields set up by radar operations.

Furthermore prior touchdown firing devices do not provide the timed evaluation interval and the abort control mechanism necessary for accurate surface control of the device.

SUMMARY OF THE INVENTION Stated in general terms, the present invention involves a device for firing an anchor member into the floor of the ocean or other body of water wherein a touchdown switch is magnetically activated to close a battery powered firing sequence time delay system. A condenser charge is allowed to reach trigger voltage, a pulse is supplied to the electrical system, igniting a squib which in turn ignites the explosive charge in the firing chamber of the anchor.

STATEMENT OF THE OBJECTS OF INVENTION It is an object of the present invention to provide an explosive firing device in an underwater anchor construction requiring no direct command link with the surface.

A further object is to provide in such anchor construction a delay arrangement wherein firing of the charge will occur within a preselected time after touchdown of the anchor.

Another object is to provide a firing device which is not susceptible to stray radio frequencies thus preventing any accidental firing thereof.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of the invention mounted on an anchor framework.

FIG. 2 is a schematic diagram showing the circuitry of the firing device in FIG. 1.

DESCRIPTION OF TI-IE PREFERRED EMBODIMENT Referring to the drawing, there i s is shown a trihedronshaped framework comprising three elongated legs 12, 14 and 16 each having pads I8 mounted on the base end thereof with braces 20, 22 and 24 interconnecting each leg for strengthening purposes substantially as shown in FIG. 1. The framework 10 is adapted to support both an explosive anchor 11 shown in outline form and the elements of the present invention which serves to control the firing of such anchor. The

invention includes a movably-mounted firing initiator rod 26 extending vertically a suitable distance below the framework and a magnet 28 secured to a sector wheel 30 which in turn is mechanically linked to the initiator rod. A magnetic switch 32 is positioned adjacent the sector wheel 30 and is designed to be activated by the field of magnetic flux surrounding magnet 28 when the latter is moved via the sector wheel into its immediate vicinity. Upon activation, switch 32 closes a batterypowered firing circuit 34 (FIG. 2) which is suitably insulated within a pressuretight cylinder 38 mounted on the framework 10. I

Thus when such framework 10 has been lowered into a body of water until it is about 2 feet from the bottom, the lower end of firing sequence initiator rod 26 (which extends vertically below the framework 10) will touch the bottom surface. Upon further lowering of the framework 10, said initiator rod is forced upward, causing the sector wheel 30 to rotate and bring magnet 28 into close proximity with the magnetic switch 32 so that the latter is activated by the field surrounding magnet 28 to close the firing circuit 34 positioned within said pressuretight cylinder 38.

As shown in FIG. I, the initiator rod 26 has a flattened foot 40 attached thereto to provide more area of contact with the muddy submerged bottom and prevents any undesirable soil penetration by the initiator rod. However, it is to be noted that the firing initiator rod may be varied in length according to the particular dimensions of the framework 10. It is pointed out, however, that any contact closure device which could initiate the firing sequence may be used such as a plumb bob or a hydrostatic pressure switch.

A pair of pressure switchs 42 and 44 (FIG. 2) are located on the framework 10 and perform as safetydevices to prevent inadvertent energizing of the firing circuit 34 while the anchor is aboard ship. Switch 42 is normally open and switch 44 is normally closed. Both switches 42 and 44 change their circuit status at a depth of about 40 feet below the surface, and, with the closing of switch 42, the coil of relay 64 is enabled. Activation of magnetic switch 32 energizes relay 64 thus moving the arms 49 and 51 to engage contacts 53 and 55, respectively. The normally-closed switch 44 opens essentially concurrently with the closing of switch 42 to remove the short circuit from across squib 48. Thus, by enabling or arming the firing circuit 34, the pressure switches 42 and 44 permit activation of the firing circuit 34 when the magnetic switch is closed.

Upon activation of the firing circuit 34, the condenser 50 indicated in FIG. 2 begins to charge through resistor 52 and reaches the trigger voltage of unijunction transistor 54 in a set period of time, determined by varying either the value of resistor 52 or the magnitude of condenser 50. However, resistors 56 and 57 are also current-limiting devices for unijunction transistor 54, and, as such, will also affect the time required for the transistor to reach trigger voltage. When transistor 54 is rendered conductive, an output pulse is generated across the resistor 56 and applied to the gate electrode of silicon-controlled rectifier 58. The latter then becomes conductive and allows the stored energy in a second condenser 60 to pass through the squib 48, causing it to ignite. Condenser 60 has been charged by the closing of pressure switch 42 and the bottom-actuated switch 32. This establishes a circuit through resistors 68 and to condenser 60, and thence through resistor 61 and conductor 47 back to the power source 76. The burning squib will then detonate an explosive charge (not shown) in the anchor firing chamber. It is to be noted that currentlimiting resistor 61 provides, in conjunction with condenser 60, a combined R-C time constant which in effect prevents the charging current of condenser 60 from exceeding the current rating of relay contact 53.

A second silicon-controlled rectifier 62 serves the purpose of preventing any inadvertent firing of squib 48 if a decision is made during a set period of time (about 5 minutes) to abort the firing of the anchor. Thus upon lifting the framework 10 from the ocean floor, the firing sequence initiator rod 26 will assume its original position. This rotates the sector wheel 30 with the magnet 28 mounted thereon away from the vicinity of magnetic switch 32, causing relay 64 to open thereby generating a pulse at 66. Such pulse is then applied to the gate electrode of silicon-controlled rectifier 62 through the voltage divider network of resistors 68 and 70. This causes rectifier 62 to become conductive, shorting the squib 48 so that any electrical energy is dissipated primarily through rectifier 62. Furthermore, current-limiting resistors 71 and 73 allow condensers 50 and 60 to discharge rapidly through relay contacts 75 and 77 respectively when the decision to recycle is made. Thus the circuit 34 become deenergized and again ready for delayed activation if the framework is once more lowered to the bottom whereupon the initiator 26 again starts the timing cycle.

A tilt switch 72 and ultra sonic pulser 74 may be incorporated in the firing system so that when the framework 10 with its supported explosive anchor are tilted on the ocean bottom more than thirty degrees, the switch 72 is closed and energizes the ultrasonic pulser 74 which signal is received in the surface vessel. Thus a decision may be made as to whether to proceed with firing the anchor or'to reset and start the timing cycle again.

It is to be noted that although this invention has been intended primarily to control the firing of an anchor, it could be used to control other devices such as core samplers and the like.

The invention may also be utilized for purposes other than igniting a squib. For example, the starting of cameras could be synchronized with the pulse generated in the firing system.

lclaim:

l. A device for controlled firing of an explosive charge in an anchor without the use of any direct command link between the anchor and a surface vessel, said device and said anchor both supported on a frame with the device comprising:

a firing circuit mounted on said frame;

means for initiating said firing circuit at a selected depth;

and

delay means incorporated in said firing circuit to allow evaluation of firing conditions prior to firing of such anchor, said delay means being a silicon controlled rectifier to dissipate electrical energy and deenergize said firing circuit.

2. The device as defined in claim I wherein said means for initiating the firing circuit is a structure activated by contact with the bottom of any body of water.

3. The device as defined in claim 1 wherein said means for initiating the firing circuit is a hydrostatic pressure switch activated at a predetermined depth below the aqueous surface.

4. The device as defined in claim 1 wherein a safety switch is incorporated in said firing circuit and adapted to prevent inadvertent energizing of the firing circuit until such device is submerged a suitable distance below the water surface.

5. A device for controlled firing of an explosive charge in an anchor without the use of any direct command link between the anchor and a surface vessel, said device and said anchor both supported on a frame with the device comprising:

a firing circuit mounted on said frame frame;

means for initiating said firing circuit at a selected depth;

delay means incorporated in said firing circuit to allow evaluation of firing conditions prior to firing of such anchor;

a tilt switch; and

a pulsing unit incorporated in said device to record at least a 30 tilt of the frame and the anchor supported thereon. 

1. A device for controlled firing of an explosive charge in an anchor without the use of any direct command link between the anchor and a surface vessel, said device and said anchor both supported on a frame with the device comprising: a firing circuit mounted on said frame; means for initiating said firing circuit at a selected depth; and delay means incorporated in said firing circuit to allow evaluation of firing conditions prior to firing of such anchor, said delay means being a silicon controlled rectifier to dissipate electrical energy and deenergize said firing circuit.
 2. The device as defined in claim 1 wherein said means for initiating the firing circuit is a structure activated by contact with the bottom of any body of water.
 3. The device as defined in claim 1 wherein said means for initiating the firing circuit is a hydrostatic pressure switch activated at a predetermined depth below the aqueous surface.
 4. The device as defined in claim 1 wherein a safety switch is incorporated in said firing circuit and adapted to prevent inadvertent energizing of the firing circuit until such device is submerged a suitable distance below the water surface.
 5. A device for controlled firing of an explosive charge in an anchor without the use of any direct command link between the anchor and a surface vessel, said device and said anchor both supported on a frame with the device comprising: a firing circuit mounted on said frame frame; means for initiating said firing circuit at a selected depth; delay means incorporated in said firing circuit to allow evaluation of firing conditions prior to firing of such anchor; a tilt switch; and a pulsing unit incorporated in said device to record at least a 30* tilt of the frame and the anchor supported thereon. 